Expanding wellbore junction

ABSTRACT

An expanding wellbore junction system, apparatus and methods are provided for forming a sealed wellbore intersection in a subterranean well. In one described method, an expandable wellbore junction is expanded within an under-reamed cavity in a wellbore. Intersecting tubular legs of the wellbore junction are then drifted using a drifting apparatus. A deflection device may be used to direct a drift of the drifting apparatus into a selected one of the wellbore junction legs.

BACKGROUND

[0001] The present invention relates generally to operations performed,and equipment utilized, in conjunction with a subterranean well and, inan embodiment described herein, more particularly provides an expandingwellbore junction method.

[0002] It is well known in the art to expand a wellbore junctiondownhole as part of a method of interconnecting multiple intersectingwellbores. However, such prior methods suffer from at least one ofseveral deficiencies. Firstly, it is difficult to seal against anexpanded tubular member, since an expanded tubular member rarely, ifever, returns to a uniform cylindrical shape. Secondly, an expandedwellbore junction typically has a somewhat misshapen form, which makesaccess therethrough, and positioning of various devices therein, verydifficult. Thirdly, the positioning, expanding, sealing, etc. stepsinvolved in utilizing an expandable wellbore junction typically requirean excessive number of trips into the well, which is time-consuming andexpensive.

[0003] From the foregoing, it can be seen that it would be quitedesirable to provide expanding wellbore junction methods, systems andapparatus which solve one or more of the above problems in the art.

SUMMARY

[0004] In carrying out the principles of the present invention, inaccordance with embodiments thereof, expanding wellbore junctionmethods, systems and apparatus are provided, each of which solves atleast one of the above problems in the art.

[0005] In one aspect of the invention, a method of forming a sealedwellbore intersection in a subterranean well is provided. The methodincludes the steps of drilling a first wellbore, under-reaming the firstwellbore, thereby forming a radially enlarged cavity, positioning anexpandable wellbore junction within the cavity, expanding the wellborejunction within the cavity, forcing a drift through at least one ofmultiple tubular legs of the wellbore junction, cementing the wellborejunction within the cavity, drilling a second wellbore through a firstone of the tubular legs of the wellbore junction, and drilling a thirdwellbore through a second one of the tubular legs of the wellborejunction.

[0006] In another aspect of the invention, an expandable wellborejunction system is provided. The system includes a wellbore junctionassembly. The wellbore junction assembly includes an expandable wellborejunction having multiple intersecting tubular legs, and an orientinglatch profile attached to the wellbore junction. The orienting latchprofile may be used to radially orient various item of equipmentrelative to the wellbore junction, such as, a deflection device, adrifting apparatus, a drilling whipstock, etc.

[0007] In yet another aspect of the invention, a drifting apparatus foruse in a wellbore junction installed in a subterranean well is provided.The apparatus includes a drift, a displacement device displacing thedrift in the wellbore junction, and a securing device securing theapparatus relative to the wellbore junction. The apparatus may bepressure actuated and may be conveyed into the well, and retrieved fromthe well, with a deflection device in a single trip into the well.

[0008] In still another aspect of the invention, a deflection deviceassembly for use in an expandable wellbore junction is provided. Theassembly includes a deflection device. The deflection device includes alaterally inclined deflection surface, a generally tubular neck, and asubstantially flexible intermediate section connected between the neckand the deflection surface, the intermediate section flexing when thedeflection device is installed in the wellbore junction, therebypermitting relative angular deflection between the deflection surfaceand the neck. This angular deflection may permit installation of thedeflection device in an imperfectly expanded wellbore junction.

[0009] In a further aspect of the invention, a method of drifting anexpandable wellbore junction in a subterranean well is provided. Themethod includes the steps of conveying a drifting apparatus into thewellbore junction, and displacing a drift of the drifting apparatus inat least one of multiple intersecting tubular legs of the wellborejunction. A pressure actuated knuckle joint or another deflection devicemay be used if desired to direct the drift into a selected one of thetubular legs.

[0010] These and other features, advantages, benefits and objects of thepresent invention will become apparent to one of ordinary skill in theart upon careful consideration of the detailed description of arepresentative embodiment of the invention hereinbelow and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a cross-sectional perspective view of a method embodyingprinciples of the present invention, wherein initial steps of the methodhave been performed;

[0012]FIG. 2 is a cross-sectional perspective view of the method,wherein an expandable junction has been positioned in an under-reamedcavity;

[0013]FIG. 3 is a cross-sectional perspective view of the method,wherein the junction has been expanded within the under-reamed cavity;

[0014]FIG. 4 is cross-sectional perspective view of the method, whereinthe expanded junction is drifted;

[0015]FIG. 5 is a partially cross-sectional view of a first driftingapparatus which may be used in the method, the apparatus embodyingprinciples of the invention;

[0016]FIG. 6 is a cross-sectional view of a junction assembly configuredfor use of the apparatus therein, the junction assembly embodyingprinciples of the invention;

[0017]FIG. 7 is a partially cross-sectional view of a second driftingapparatus which may be used in the method, the second apparatusembodying principles of the invention;

[0018]FIG. 8 is a cross-sectional perspective view of the method,wherein the expanded junction is cemented within the cavity;

[0019]FIG. 9 is a cross-sectional perspective view of the method,wherein a wellbore is drilled through one lower leg of the junction; and

[0020]FIG. 10 is a cross-sectional perspective view of the method,wherein another wellbore is drilled through another lower leg of thejunction.

DETAILED DESCRIPTION

[0021] Representatively illustrated in FIGS. 1-4 and 8-10 is anexpanding wellbore junction method 10 which embodies principles of thepresent invention. In the following description of the method 10 andother apparatus and methods described herein, directional terms, such as“above”, “below”, “upper”, “lower”, etc., are used only for conveniencein referring to the accompanying drawings. Additionally, it is to beunderstood that the various embodiments of the present inventiondescribed herein may be utilized in various orientations, such asinclined, inverted, horizontal, vertical, etc., and in variousconfigurations, without departing from the principles of the presentinvention.

[0022] In the method 10, an expandable wellbore junction 12 ispositioned within an under-reamed cavity 14, the wellbore junction isexpanded outward, a drift 16 is displaced in each of three intersectingbranches or legs 18, 20, 22 of the wellbore junction, and the wellborejunction is cemented within the cavity. Additional wellbores 24, 26 maythen be drilled through each of the lower legs 20, 22 of the wellborejunction 12. The method 10 provides a stable, sealed and strong wellboreintersection which is efficient and economical to install.

[0023] Referring specifically now to FIG. 1, initial steps of the method10 have been performed. A wellbore 28 has been drilled in the earth anda tubular string has been installed in the wellbore. The wellbore 28 mayextend to the earth's surface, to another wellbore, or to any otherpoint of origin.

[0024] The tubular string 30 may be a casing string, a liner string, orany other type of tubular string. The tubular string 30 may be cementedin the wellbore 28 upon installation, or the cementing may be performedlater in the method 10.

[0025] The cavity 14 is then formed in the wellbore 28. As depicted inFIG. 1, the cavity 14 is formed by under-reaming the wellbore 28, sothat the cavity is radially enlarged relative to the wellbore 28 abovethe cavity. However, it is to be understood that other means ofenlarging the wellbore 28 to accommodate the expanded wellbore junction12 may be used in keeping with the principles of the invention. Forexample, the wellbore 28 could be extended laterally withoutunder-reaming. Thus, any means of forming the cavity 14 may be used.

[0026] Note that the wellbore 28 may extend below the cavity 14 anydistance, or not at all. If the wellbore 28 is drilled to its terminaldepth prior to installation of the expandable wellbore junction 12, thenthere may be no need to drill the wellbore 24 through the expandedwellbore junction as depicted in FIG. 9. As described herein, it isassumed that the wellbore 28 extends somewhat below the cavity 14, butthe wellbore is further drilled to form the wellbore 24 below thewellbore junction 12 after it is installed. However, it should beunderstood that this is merely one example of the many various ways inwhich the principles of the invention may be practiced. Referringspecifically now to FIG. 2, the wellbore junction 12 is positioned inthe cavity 14 as a part of an overall wellbore junction assembly 32. Onepreferred example of the wellbore junction assembly 32 is depicted inFIG. 6 and is described in greater detail below. However, the specificequipment used in the junction assembly 32 described herein is notrequired for practicing the principles of the invention, as a variety ofchanges may be made to the assembly, if desired to suit a particularapplication.

[0027] As depicted in FIG. 2, the wellbore junction 12 is in itscollapsed configuration. The junction 12 is preferably made ofinterconnected generally tubular metal elements which, after they areconnected together, are mechanically collapsed so that the junction maypass through the tubular string 30. The junction 12 is preferablyexpanded by inflating, that is, by applying pressure to its interior toforce the tubular elements to expand outward and assume their priorinterconnected shapes, as described below. However, any type of wellborejunction, made of any type of material and expanded by any means, may beused in keeping with the principles of the invention.

[0028] The junction assembly 32 is preferably composed substantially ofliner 34 above the wellbore junction 12. The liner 34 is anchored to thetubular string 30, for example, using a conventional liner hanger (notshown) of the type well known to those skilled in the art. Other meansof securing the junction assembly 32 to the tubular string 30, or othermeans of anchoring the junction assembly so that the junction 12 ispositioned in the cavity 14, may be used in keeping with the principlesof the invention.

[0029] Prior to anchoring the junction assembly 32, the leg 22 isradially oriented so that, when the junction 12 is expanded and cementedwithin the cavity 14, the expanded leg will face in a desired directionfor drilling the wellbore 26. For convenience of description, the leg 22will be referred to as a “lateral” leg, since in the illustratedembodiment the leg 22 extends somewhat laterally relative to theremainder of the junction 12, but it is to be clearly understood that itis not necessary for the leg 22 to extend laterally at all.

[0030] For reasons explained below, it may be desired to orient thelateral leg 22 toward the high side of the wellbore 28 when the wellboreis not vertical. Other orientations may be desired to suit othercircumstances, and in some instances a particular orientation for eitherof the legs 20, 22 may not be desired.

[0031] Referring specifically now to FIG. 3, the junction 12 has beenradially outwardly expanded by applying pressure to the junctionassembly 32, thereby creating a pressure differential from the interiorto the exterior of the junction. In its expanded configuration, thelateral leg 22 extends outward from the junction assembly 32 in thecavity 14. However, it is not expected that the junction 12 willperfectly resume its pre-collapsed shape when inflated. Unfortunately,such imperfect expansion can restrict access and flow through thejunction 12, prevent certain equipment from being properly positioned,oriented, connected, etc. to the junction, and may cause other problems.

[0032] Referring specifically now to FIG. 4, the method 10 includesprovisions for overcoming the difficulties caused by imperfect inflationof the junction 12. The drift 16 is conveyed into the junction assembly32 as part of an overall drifting apparatus 36. The drifting apparatus36 as depicted in FIG. 4 includes the drift 16 and a tubular string 38,such as segmented drill pipe, for conveying the apparatus 36 downhole.The apparatus 36 may include other or different elements in keeping withthe principles of the invention.

[0033] As used herein, the term “drift” is used to indicated a toolwhich is forced through a passage to thereby reform the interior of thepassage, so that it takes on a desired shape. In the representativelyillustrated method 10, the drift 16 has a round cross-sectional shape,since it is desired to produce a substantially cylindrical shape in thelegs 18, 20, 22 of the junction 12. However, other shapes may be used inkeeping with the principles of the invention. The legs 18, 20, 22 may beexpanded when the drift 16 is displaced therethrough.

[0034] Using the apparatus 36, each of the legs 18, 20, 22 may bedrifted (i.e., physically extended outward to a known desired dimension)by displacing the drift 16 therein. For example, to drift the upper leg18, the apparatus 36 is lowered by the tubular string 38, so that thedrift 16 passes through the leg, thereby reforming the inner diameter ofthe leg so that it assumes a substantially cylindrical shape havingsubstantially the same dimension as the outer diameter of the drift.

[0035] If the lower leg 20 is substantially coaxial with the upper leg18, or possibly in other circumstances, the lower leg may be drifted inthe same manner as the upper leg. Of course, the main body of thejunction 12 between the upper and lower legs 18, 20 may also be driftedin the same manner. However, it should be understood that it is notnecessary for the upper and lower legs 18, 20 to be substantiallycoaxial, or for the main body of the junction 12 to extend substantiallylinearly between the upper and lower legs, in keeping with theprinciples of the invention.

[0036] Since the lateral leg 22 of the representatively illustratedjunction 12 is not coaxial with the upper leg 18, the drifting apparatus36 may include provisions for directing the drift 16 to enter thelateral leg. As depicted in FIG. 4, the apparatus 36 includes aconventional knuckle joint 40 to angularly offset the drift 16 relativeto the tubular string 38 above the knuckle joint.

[0037] The knuckle joint 40 may be any type of knuckle joint, forexample, a mechanical or pressure actuated knuckle joint, etc.Preferably, the knuckle joint 40 is pressure actuated, so that when thedrift 16 has been positioned in the junction 12, pressure may be appliedto the tubular string 38 to radially outwardly displace the drift. Afterthe knuckle joint 40 has been actuated, the drift 16 is displaced in thelateral leg 22, for example, by lowering the tubular string 38.

[0038] Referring specifically now to FIG. 5, an alternate driftingapparatus 42 is representatively illustrated. The apparatus 42 may beused in place of the apparatus 36 in the method 10. Other means ofdrifting the junction 12 may be used in keeping with the principles ofthe invention.

[0039] Instead of using manipulations of the tubular string 38 todisplace the drift 16 in the legs 18, 20, 22 of the junction 12, theapparatus 42 utilizes a pressure actuated displacement device 44. Asdepicted in FIG. 5, the displacement device 44 is an axial extensiondevice which includes a piston 46 exposed to pressure in the tubularstring 38.

[0040] When pressure in the tubular string 38 exceeds a predeterminedlevel, shear pins or shear ring 48 shear, permitting the piston 46 todisplace downward. Other types of shear members, or other types ofrelease mechanisms may be used in place of the shear pins 48. The piston46 is attached to the drift 16, so that as the piston 46 displacesdownward, so does the drift.

[0041] To anchor the extension device 44 in place while the drift 16 isbeing displaced in the junction 12, an anchoring or securing device 49is included in the apparatus 42. The anchoring device 49 includes atleast one gripping structure 50, such as a slip of the typeconventionally used on packers, liner hangers, etc.

[0042] The gripping structure 50 is radially outwardly extended when apredetermined pressure is applied to the tubular string 38. The pressureused to actuate the anchoring device 49 is preferably less than thepressure used to shear the pins 48. Other types of anchoring devices andgripping structures may be used in the apparatus 42 in keeping with theprinciples of the invention. For example, the gripping structure 50could be outwardly extended by manipulation of the tubular string 38,etc.

[0043] When outwardly extended, the gripping structure 50 grippinglyengages a portion of the junction assembly 32, such as in a section ofliner 34, thereby fixing the axial position of the drifting apparatus 42in the junction assembly. Such gripping engagement also preferably fixesthe radial orientation of the drifting apparatus 42 relative to thejunction 12, for reasons explained below.

[0044] The drifting apparatus 42 may also, or alternatively, include asecuring device or latch 52 to aid in positioning the drifting apparatus42 in the junction assembly 32. For example, the latch 52 may be used toprovide an indication to an operator at the surface that the driftingapparatus 42 is appropriately positioned in the junction assembly 32.The latch 52 may also releasably retain the drifting apparatus 42 inposition in the junction assembly 32 until the anchoring device 49 isactuated.

[0045] The latch 52 is configured to engage a latch profile 54 includedin the junction assembly 32 (see FIG. 6). The latch profile 54 may bepositioned anywhere in the junction assembly 32, and any number of latchprofiles may be used, but preferably at least one latch profile ispositioned above the upper leg 18 of the junction 12, and another latchprofile 56 is positioned below the lower leg 20, as depicted in FIG. 6.

[0046] The upper latch profile 54 permits the drifting apparatus 42 tobe appropriately positioned in the junction assembly 32 before, duringand after drifting the upper leg 18. The lower latch profile 56 permitsappropriate positioning of other equipment in the junction assembly 32(as described below) after the drifting of at least the upper leg 18 andthe lower leg 20.

[0047] For reasons explained below, the latch 52 is preferably of thetype known to those skilled in the art as an orienting latch, and theprofiles 54, 56 are preferably orienting latch profiles. That is, theengagement between the latch 52 and either of the latch profiles 54, 56serves to radially orient the latch relative to the latch profile. Thus,when the latch 52 in the drifting apparatus 42 is properly engaged withthe latch profile 54, the drifting apparatus is radially oriented in aparticular direction relative to the junction assembly 32. A suitablelatch and latch profile which may be used for the latch 52 and profile54 is available from Halliburton Energy Services, Inc. as the Sperry-SunLatch Coupling with Orienting Sub.

[0048] Note that it is not necessary in the method 10 for the driftingapparatus 42 to be radially oriented relative to the junction assembly32. However, when such radial orientation is desired, as explainedbelow, the latch 52 and profile 54 are available to perform thisfunction. For example, the latch 52 may be included in the driftingapparatus 36 depicted in FIG. 4 to radially orient the apparatus 36 sothat when the knuckle joint 40 is actuated, the drift 16 is directed inthe appropriate radial direction to displace toward the lateral leg 22of the junction 12.

[0049] The drifting apparatus 42 may be used to drift the upper leg 18as follows: Convey the drifting apparatus 42 on the tubular string 38into the junction assembly 32. Engage the latch 52 with the latchprofile 54 and apply a predetermined pressure to the tubular string 38,to thereby actuate the anchoring device 49 and fix the axial and radialposition of the apparatus 42 in the assembly 32. Apply an increasedpredetermined pressure to the tubular string 38 to thereby actuate theextension device 44 (i.e., displace the piston 46) and thereby displacethe drift 16 in the leg 18. When the drifting is completed, pressure inthe tubular string 38 may be relieved to enable the gripping structure50 to retract for retrieval of the apparatus 42 from the well.

[0050] If the extension device 44 is suitably configured, and if thejunction legs 18, 20 are substantially coaxial, both of the junctionlegs 18, 20 may be drifted in a single trip into the well by continuingto displace the drift 16 downward through the main body of the junction12 and into the lower leg 20 after drifting the upper leg 18.Alternatively, the legs 18, 20 may be drifted in separate trips into thewell.

[0051] If, as described above, the junction 12 is radially oriented inthe cavity 14 so that the lateral leg 22 faces toward the high side ofthe wellbore 28, then equipment conveyed through the junction from abovewill enter the lower leg 20, due to the force of gravity. This situationis advantageous in that it requires no special equipment or proceduresto select the lower leg 20 for entry. Another benefit is that it enablesselection of the lateral leg 22 for entry by using gravity sensingequipment, such as high side detectors, MWD tools, etc.

[0052] The upper latch profile 54 provides yet another method ofselecting the lateral leg 22 for entry. Preferably, before and/or duringrunning the junction assembly 32 into the well, the latch profile 54 isoriented so that it has a known radial orientation relative to thelateral leg 22. For example, since the distance between the junction 12and the position of the latch profile 54 in the junction assembly 32 maybe too great to conveniently fix the radial orientation of the latchprofile relative to the junction prior to running the assembly into thewell, a tool, such as a gyroscope, may be used to indicate the relativeradial orientation of the lateral leg 22 after the junction has been runinto the well and when the latch profile is connected to the assembly.

[0053] Of course, other means of radially orienting the latch profile 54(or the latch profile 56) relative to the lateral leg 22 may be used inkeeping with the principles of the invention. In addition, the latchprofile 54 could be specifically oriented relative to another portion ofthe junction 12, or another portion of the junction assembly 32, withoutdeparting from the principles of the invention.

[0054] In the representatively illustrated method 10, when it is desiredto drift the lateral leg 22, a modification is made to the driftingapparatus 42 to permit the drift 16 to enter the lateral leg. Referringspecifically now to FIG. 7, a deflection device assembly 58 is added tothe drifting apparatus 42 to deflect the drift 16 toward the lateral leg22.

[0055] The deflection device assembly 58 includes a deflection device60, a latch 62, a releasing device 64, an upwardly facing muleshoe 66and a generally tubular housing 68. The housing 68 is attached to thedisplacement device 44 of the drifting apparatus 42, so that thedeflection device assembly 58 is conveyed into the well as part of thedrifting apparatus.

[0056] However, the housing 68 is releasably attached to the deflectiondevice assembly 58 using the releasing device 64. The releasing device64 includes lugs 70 which retract when a predetermined pressure isapplied to the tubular string 38, to thereby release the remainder ofthe deflection device assembly 58 for axial displacement relative to therest of the drifting apparatus 42. The lugs 70 also maintain a radialorientation of the deflection device assembly 58 relative to the latch52, until the lugs are retracted. Other types of releasing devices, suchas shear pins, J-slots, etc., may be used in place of, or in additionto, the releasing device 64.

[0057] The deflection device 60 includes a laterally inclined deflectionsurface 72, an upper generally tubular neck 74, and an intermediatesection 76 extending between the neck and the deflection surface. Asdescribed above, the junction 12 is expected to be somewhat imperfectlyreformed after it is inflated. Since the deflection device 60 isconfigured to extend into both the upper leg 18 and the lower leg 20when installed in the junction 12, the intermediate section 76 ispreferably substantially flexible. In this manner, a degree of angularmisalignment between the upper and lower legs 18, 20 may be accommodatedby flexing in the intermediate section 76.

[0058] In the method 10, the drifting apparatus 42 including thedeflection device assembly 58 is conveyed into the well after both theupper and lower legs 18, 20 have been drifted as described above. Whenthe latch 52 engages the latch profile 54, the deflection device 60 isradially oriented so that the deflection surface 72 faces toward thelateral leg 22. The tubular string 38 is lowered further, therebycausing the latch 62 on the deflection device assembly 58 to engageanother latch profile 78 in the junction assembly 32.

[0059] Since, at this point, the deflection device 60 is alreadyradially oriented relative to the junction 12, this engagement betweenthe latch 62 and the profile 78 preferably does not radially orient thedeflection device, but serves instead to axially and rotationally securethe deflection device assembly 58 in the junction assembly 32. However,engagement between the latch 62 and the profile 78 could radially orientthe deflection device 60 if desired, without departing from theprinciples of the invention. A suitable latch and profile which may beused for the latch 62 and profile 78 is available from HalliburtonEnergy Services, Inc. as the Sperry-Sun Double Collet Latch Coupling.

[0060] When the latch 62 engages the profile 78, the neck 74 ispreferably positioned in the upper leg 18 and a bull plug 80 attached toa lower end of the deflection device 60 is positioned in the lower leg20. As described above, this positioning of the deflection device 60 inthe junction 12 may result in flexing of the intermediate section 76 toaccommodate any misalignment between the upper and lower legs 18, 20.

[0061] A predetermined pressure is then applied to the tubular string 38to retract the lugs 70 and release the deflection device assembly 58 fordisplacement relative to the remainder of the drifting apparatus 42.Preferably, the pressure required to retract the lugs 70 is less thanthe pressure required to extend the gripping structure 50, and is lessthan the pressure required to shear the shear pins 48 to thereby permitthe piston 46 of the displacement device 44 to displace, so that thedeflection device assembly 58 is released prior to anchoring thedrifting apparatus 42 and prior to displacing the drift 16 using thedisplacement device.

[0062] After the deflection device assembly 58 has been released, thedrifting apparatus 42 is operated as described above, i.e., by applyingan increased pressure to the tubular string 38 to extend the grippingstructure 50, and then further increasing the pressure to displace thedrift 16 downward. However, when the drift 16 eventually contacts thedeflection surface 72, it is deflected laterally, so that it enters thelateral leg 22, instead of the lower leg 20. Further displacement of thedrift 16 in the lateral leg 22 acts to drift the lateral leg to adesired inner dimension or geometry.

[0063] After the lateral leg 22 has been drifted, pressure on thetubular string 38 is relieved, thereby permitting the gripping structure50 to retract. The tubular string 38 may then be raised to retrieve thedrifting apparatus 42, disengaging the latch 52 from the latch profile54. The deflection device assembly 58 may be retrieved along with theremainder of the drifting apparatus 42 by provision of a radiallyenlarged shoulder 82 on a mandrel 84 extending between the displacementdevice 44 and the drift 16. When the drifting apparatus 42 is raised,the mandrel 84 is also raised, causing the shoulder 82 to contact ano-go shoulder 86 attached to the deflection device 60. This contactbetween the shoulders 82, 86 permits retrieval of the deflection deviceassembly 58 along with the remainder of the drifting apparatus 42. Thus,the drifting apparatus 42 including the deflection device assembly 58may be installed in the junction assembly 32 and retrieved therefrom ina single trip into the well.

[0064] Note that many other means of positioning the deflection device60 in the junction assembly 32 may be used in keeping with theprinciples of the invention. For example, the deflection device 60 couldbe radially oriented relative to the junction 12 by attaching a latch,such as the latch 52, between the bull plug 80 and the deflectiondevice. This latch would engage the latch profile 56 below the lower leg20, thereby radially orienting and axially securing the deflectiondevice 60 relative to the junction 12.

[0065] Referring specifically now to FIG. 8, the junction 12 is cementedin the cavity 14 after the drifting operations are completed. As usedherein, the terms “cement” and “cementing” are used broadly to encompassthe use of any hardenable liquid or slurry to secure and seal equipmentin a wellbore, although, technically speaking, the hardenable liquid orslurry may not actually contain a cementitious material. For example,the use of an epoxy or other polymer-containing hardenable liquid may beconsidered “cementing”, and the hardenable fluid or slurry may bereferred to as “cement”. As used herein, the terms “harden” and“hardenable” are used broadly to indicate increased rigidity andstrength, and such terms encompass the use of materials such as gelswhich, although they may not solidify, become more rigid and haveincreased strength.

[0066] To cement the junction 12 in the cavity 14, another tubularstring 88 is conveyed into the junction assembly 32. A sealing device orstinger 90 attached to a lower end of the tubular string 88 is stunginto a seal bore 92 of a cementing device 94 attached to a lower end ofthe lower leg 20. The cementing device 94 includes at least one valve 96selectively permitting and preventing flow through the cementing device.

[0067] The valve 96 is closed when pressure is applied to the interiorof the junction 12 to inflate it. The valve 96 is opened when it isdesired to flow cement 98 from the tubular string 88 through thecementing device 94, and outward into the cavity 14 surrounding thejunction 12. The tubular string 88 is retrieved from the well along withthe stinger go when the cementing operation is completed.

[0068] Referring specifically now to FIG. 9, after the cement 98 hashardened, the cementing device 94 may be drilled through by conveying acutting device, such as one or more mill or drill 100 into the junctionassembly 32. The drill 100 may also be used to form the wellbore 24extending outwardly from the lower leg 20. As described above, thewellbore 28 may extend below the cavity 14 prior to the junction 12being positioned therein, in which case the drill 100 may be used tofurther extend the wellbore 28.

[0069] Referring specifically now to FIG. 10, The wellbore 26 may beformed extending outwardly from the lateral leg 22 using the drill 100by first positioning a deflection device, such as a drilling whipstock102, in the junction 12. Note that the whipstock 102 has an orientinglatch 104 attached to a lower end thereof for engagement with the latchprofile 56 below the lower leg 20. In this manner, the whipstock 102 isradially oriented and axially secured relative to the junction 12 whenthe latch 104 is engaged with the profile 56.

[0070] Alternatively, the same deflection device 60 used to drift thelateral leg 22 may be used as the drilling whipstock 102. After thewellbores 24, 26 have been drilled, or either of them has been drilled,tubular strings, such as liners, screens, etc. may be positioned in thewellbores and cemented therein, or the wellbores may be completed openhole if desired. If tubular strings are used, these tubular strings maybe conveniently attached and sealed to the legs 20, 22 usingconventional techniques, such as by using liner hangers, packers, etc.,since the legs have been previously drifted and, thus, are well suitedfor sealing engagement and/or attachment thereto. Note that the method10 thus provides a sealed wellbore intersection that is convenient andeconomical in installation, while permitting unhindered access to eachwellbore and pressure isolation between the interior of the junction 12and a formation surrounding the junction.

[0071] Of course, a person skilled in the art would, upon a carefulconsideration of the above description of representative embodiments ofthe invention, readily appreciate that many modifications, additions,substitutions, deletions, and other changes may be made to thesespecific embodiments, and such changes are contemplated by theprinciples of the present invention. Accordingly, the foregoing detaileddescription is to be clearly understood as being given by way ofillustration and example only, the spirit and scope of the presentinvention being limited solely by the appended claims and theirequivalents.

What is claimed is:
 1. An expandable wellbore junction system,comprising: a wellbore junction assembly including: an expandablewellbore junction having multiple intersecting tubular legs; and anorienting latch profile attached to the wellbore junction.
 2. The systemaccording to claim 1, further comprising a drifting apparatus positionedat least partially in the junction assembly, the drifting apparatusbeing radially oriented relative to the wellbore junction by engagementwith the orienting latch profile.
 3. The system according to claim 2,wherein the drifting apparatus includes a drift which is displaced in atleast one of the tubular legs of the wellbore junction, therebyreforming an interior geometry of the at least one of the tubular legs.4. The system according to claim 3, further comprising a deflectiondevice releasably installed in the wellbore junction.
 5. The systemaccording to claim 4, wherein the deflection device is radially orientedrelative to the wellbore junction by engagement of the driftingapparatus with the orienting latch profile.
 6. The system according toclaim 4, wherein deflection device deflects the drift to displace towardthe at least one of the wellbore junction tubular legs.
 7. The systemaccording to claim 1, further comprising a drifting apparatus whichincludes a drift, a gripping structure and an axial extension device,the gripping structure anchoring the drifting apparatus to the wellborejunction assembly, and the extension device displacing the drift in atleast one of the wellbore junction tubular legs.
 8. The system accordingto claim 7, wherein the gripping structure is outwardly extended intogripping engagement with the wellbore junction assembly by a firstpredetermined pressure applied to the drifting apparatus.
 9. The systemaccording to claim 8, wherein the extension device displaces the driftin response to a second predetermined pressure applied to the driftingapparatus.
 10. The system according to claim 9, wherein the secondpressure is greater than the first pressure.
 11. The system according toclaim 9, further comprising a deflection device releasably attached tothe drifting apparatus, the deflection device being released fordisplacement of the drifting apparatus relative to the deflection deviceby application of a third predetermined pressure to the driftingapparatus.
 12. The system according to claim 11, wherein the thirdpressure is less than each of the first and second pressures.
 13. Thesystem according to claim 1, wherein the wellbore junction assemblyfurther includes a cementing device attached to the wellbore junction,the cementing device being configured to direct cement flow outwardlyfrom the wellbore junction assembly.
 14. The system according to claim13, wherein the cementing device includes a valve selectively permittingand preventing cement flow through the cementing device.
 15. The systemaccording to claim 13, further comprising a tubular string disposed inthe wellbore junction assembly, cement flowing through the tubularstring to the cementing device.
 16. The system according to claim 15,wherein the tubular string is sealingly engaged with the cementingdevice.
 17. The system according to claim 1, further comprising awhipstock engaged with the orienting latch profile, thereby radiallyorienting the whipstock relative to the wellbore junction, and a cuttingdevice deflected off of the whipstock so that the cutting device forms awellbore extending outwardly from one of the wellbore junction tubularlegs.
 18. The system according to claim 1, wherein the wellbore junctionassembly is attached to a tubular string in a first wellbore and extendsoutwardly from the tubular string into an enlarged cavity formed in thefirst wellbore.
 19. The system according to claim 18, wherein thewellbore junction is expanded outward within the cavity due to pressureapplied within the wellbore junction, the wellbore junction is cementedwithin the cavity, and at least first and second wellbores are formedthrough the wellbore junction tubular legs and through cementsurrounding the wellbore junction in the cavity.
 20. A method of forminga sealed wellbore intersection in a subterranean well, the methodcomprising the steps of: drilling a first wellbore; under-reaming thefirst wellbore, thereby forming a radially enlarged cavity; positioningan expandable wellbore junction within the cavity; expanding thewellbore junction within the cavity; forcing a drift through at leastone of multiple tubular legs of the wellbore junction; cementing thewellbore junction within the cavity; drilling a second wellbore througha first one of the tubular legs of the wellbore junction; and drilling athird wellbore through a second one of the tubular legs of the wellborejunction.
 21. The method according to claim 20, further comprising thestep of installing a tubular string in the first wellbore after thefirst wellbore drilling step, and wherein the expandable wellborejunction positioning step further comprises attaching the wellborejunction to the tubular string.
 22. The method according to claim 21,wherein the attaching step further comprises securing the wellborejunction so that in the expanding step the second tubular leg isdirected toward a desired orientation for drilling the third wellbore.23. The method according to claim 20, wherein the positioning stepfurther comprises installing the wellbore junction within the cavity aspart of a junction assembly including an orienting latch profile. 24.The method according to claim 23, wherein in the installing step, theorienting latch profile is positioned between the wellbore junction andthe tubular string.
 25. The method according to claim 23, wherein in theinstalling step, the wellbore junction is positioned between theorienting latch profile and the tubular string.
 26. The method accordingto claim 23, wherein the drift forcing step further comprisespositioning a drifting apparatus within the junction assembly, andengaging the drifting apparatus with the orienting latch profile,thereby securing the drifting apparatus within the junction assembly andradially orienting the drifting apparatus relative to the junctionassembly.
 27. The method according to claim 26, wherein the driftingapparatus engaging step further comprises radially orienting adeflection device relative to the junction assembly, so that the driftis directed to extend toward the second tubular leg of the wellborejunction.
 28. The method according to claim 23, wherein the secondwellbore drilling step further comprises engaging a whipstock with theorienting latch profile, thereby radially orienting the whipstockrelative to the wellbore junction.
 29. The method according to claim 20,wherein the positioning step further comprises installing the wellborejunction within the cavity as part of a junction assembly including acementing device for flowing cement outward into the cavity.
 30. Themethod according to claim 29, wherein in the positioning step thecementing device is attached to the first tubular leg outwardly disposedrelative to an intersection between the first and second tubular legs.31. The method according to claim 29, wherein the cementing step furthercomprises positioning a tubular string within the junction assembly,connecting the tubular string to the cementing device, and flowingcement through the tubular string and outward through the cementingdevice.
 32. The method according to claim 31, wherein the connectingstep further comprises sealingly engaging the tubular string with thejunction assembly.
 33. The method according to claim 29, wherein thecementing step further comprises opening a valve within the cementingdevice to thereby permit cement flow through the cementing device. 34.The method according to claim 33, wherein in the expanding step thecementing device valve is closed, thereby permitting creation of apressure differential between an interior and exterior of the junctionassembly.
 35. The method according to claim 20, wherein the driftforcing step further comprises installing a drifting apparatus in thewellbore junction.
 36. The method according to claim 35, wherein thedrift forcing step further comprises applying pressure to the driftingapparatus to thereby force the drift to displace within at least one ofthe tubular legs of the wellbore junction.
 37. The method according toclaim 36, wherein the applying pressure step further comprisesdisplacing a piston, thereby causing displacement of the drift.
 38. Themethod according to claim 36, wherein the applying pressure step furthercomprises outwardly extending a gripping structure, thereby anchoringthe drifting apparatus relative to the wellbore junction.
 39. The methodaccording to claim 35, wherein the installing step further comprisesengaging the drifting apparatus with an orienting latch profile attachedto the wellbore junction, thereby radially orienting the driftingapparatus relative to the wellbore junction.
 40. The method according toclaim 39, wherein the installing step further comprises installing adeflection device in the wellbore junction, and wherein the radiallyorienting step further comprises radially orienting the deflectiondevice relative to the wellbore junction.
 41. The method according toclaim 35, wherein the installing step further comprises installing adeflection device in the wellbore junction, and wherein the driftforcing step further comprises deflecting the drift off of thedeflection device.
 42. The method according to claim 41, wherein theinstalling step further comprises installing the drifting apparatus anddeflection device in the wellbore junction in a single trip into thewell.
 43. The method according to claim 41, wherein the installing stepfurther comprises conveying the deflection device into the wellborejunction attached to the drifting apparatus.
 44. The method according toclaim 43, wherein the installing step further comprises engaging anorienting profile, thereby radially orienting both the driftingapparatus and the deflection device relative to the wellbore junction.45. The method according to claim 44, wherein the installing stepfurther comprises securing the deflection device relative to thewellbore junction, and then anchoring the drifting apparatus relative tothe wellbore junction.
 46. The method according to claim 45, wherein theinstalling step further comprises detaching the deflection device fromthe drifting apparatus after the deflection device securing step andprior to the drifting apparatus anchoring step.
 47. The method accordingto claim 46, wherein the detaching step is performed by applyingpressure to the drifting apparatus.
 48. The method according to claim45, wherein the anchoring step is performed by outwardly extending agripping structure from the drifting apparatus.
 49. The method accordingto claim 20 further comprising the step of retrieving a deflectiondevice from within the wellbore junction by engaging an enlargedshoulder attached to the drift with a shoulder attached to thedeflection device.
 50. A drifting apparatus for use in a wellborejunction installed in a subterranean well, the apparatus comprising: adrift; a displacement device displacing the drift in the wellborejunction; and a securing device securing the apparatus relative to thewellbore junction.
 51. The apparatus according to claim 50, wherein thedisplacement device displaces the drift in response to pressure appliedto the displacement device.
 52. The apparatus according to claim 51,wherein the displacement device displaces the drift in response topressure applied to a tubular string connected to the driftingapparatus.
 53. The apparatus according to claim 51, wherein thedisplacement device includes a piston exposed to pressure applied to thedisplacement device, the piston being attached to the drift, and thepiston displacing the drift when a predetermined pressure is applied tothe displacement device.
 54. The apparatus according to claim 50,wherein the securing device includes an outwardly extendable grippingstructure.
 55. The apparatus according to claim 54, wherein the grippingstructure includes at least one slip.
 56. The apparatus according toclaim 54, wherein the gripping structure outwardly extends from thedrifting apparatus when a predetermined pressure is applied to theapparatus.
 57. The apparatus according to claim 50, wherein the securingdevice includes a latch which engages a latch profile attached to thewellbore junction.
 58. The apparatus according to claim 57, wherein thelatch is an orienting latch and the latch profile is an orienting latchprofile, whereby the drifting apparatus is radially oriented relative tothe wellbore junction when the latch engages the latch profile.
 59. Theapparatus according to claim 58, further comprising a deflection devicefor deflecting the drift relative to the wellbore junction, thedeflection device being radially oriented relative to the wellborejunction when the latch is engaged with the latch profile.
 60. Theapparatus according to claim 50, further comprising a deflection devicereleasably attached to the displacement device, the deflection devicelaterally deflecting the drift when the displacement device displacesthe drift in the wellbore junction.
 61. The apparatus according to claim60, wherein the deflection device is released, permitting relativedisplacement between the displacement device and the deflection device,when a predetermined pressure is applied to the drifting apparatus. 62.The apparatus according to claim 60, further comprising an enlargedshoulder attached to the drift, and a no-go shoulder attached to thedeflection device, engagement between the enlarged shoulder and theno-go shoulder permitting retrieval of the deflection device with thedisplacement device after the deflection device is released fordisplacement relative to the displacement device.
 63. A deflectiondevice assembly for use in an expandable wellbore junction, the assemblycomprising: a deflection device including: a laterally inclineddeflection surface; a generally tubular neck; and a substantiallyflexible intermediate section connected between the neck and thedeflection surface, the intermediate section flexing when the deflectiondevice is installed in the wellbore junction, thereby permittingrelative angular deflection between the deflection surface and the neck.64. The assembly according to claim 63, further comprising a wellborejunction drifting apparatus disposed at least partially in thedeflection device neck.
 65. The assembly according to claim 63, furthercomprising a latching device attached to the deflection device.
 66. Theassembly according to claim 63, further comprising an upwardly facingmuleshoe attached to the deflection device.
 67. The assembly accordingto claim 63, further comprising a pressure actuated releasing deviceattached to the deflection device.
 68. The assembly according to claim63, further comprising an orienting latch attached to the deflectiondevice, the orienting latch radially orienting the deflection surfacerelative to the wellbore junction.
 69. A method of drifting anexpandable wellbore junction in a subterranean well, the methodcomprising the steps of: conveying a drifting apparatus into thewellbore junction; and displacing a drift of the drifting apparatus inat least one of multiple intersecting tubular legs of the wellborejunction.
 70. The method according to claim 69, wherein the conveyingstep further comprises conveying a deflection device into the wellborejunction, the deflection device being configured to deflect the drift toenter a selected one of the wellbore junction tubular legs.
 71. Themethod according to claim 70, wherein in the conveying step the driftingapparatus and deflection device are conveyed into the wellbore junctionin a single trip into the well.
 72. The method according to claim 71,further comprising the step of retrieving the drifting apparatus anddeflection device from the well.
 73. The method according to claim 72,wherein the conveying and retrieving steps are performed in the singletrip into the well.
 74. The method according to claim 70, furthercomprising the step of radially orienting the deflection device relativeto the wellbore junction.
 75. The method according to claim 74, whereinthe radially orienting step further comprises engaging an orientingprofile attached to the wellbore junction.
 76. The method according toclaim 75, wherein the engaging step further comprises engaging a latchof the drifting apparatus with the orienting profile.
 77. The methodaccording to claim 74, wherein the radially orienting step furthercomprises simultaneously radially orienting both the drifting apparatusand the deflection device relative to the wellbore junction.
 78. Themethod according to claim 77, further comprising the step of securingthe deflection device relative to the wellbore junction after theradially orienting step.
 79. The method according to claim 78, whereinthe securing step further comprises engaging an engagement deviceattached to the deflection device with an engagement profile attached tothe wellbore junction.
 80. The method according to claim 78, furthercomprising the step of releasing the drifting apparatus for displacementrelative to the deflection device after the securing step.
 81. Themethod according to claim 80, wherein the releasing step is performed byapplying a first predetermined pressure to the drifting apparatus. 82.The method according to claim 80, further comprising the step ofanchoring the drifting apparatus relative to the wellbore junction afterthe releasing step.
 83. The method according to claim 82, wherein theanchoring step is performed by applying a second predetermined pressureto the drifting apparatus.
 84. The method according to claim 82, whereinthe anchoring step further comprises outwardly extending a grippingstructure from the drifting apparatus.
 85. The method according to claim82, further comprising the steps of displacing the drift, and deflectingthe drift off of the deflection device.
 86. The method according toclaim 85, wherein the displacing step is performed by applying a thirdpredetermined pressure to the drifting apparatus.
 87. The methodaccording to claim 85, wherein the displacing and deflecting steps areperformed after the anchoring step.
 88. The method according to claim69, wherein in the conveying step the drifting apparatus includes atubular string having a knuckle joint interconnected therein, andfurther comprising the step of actuating the knuckle joint to direct thedrift toward the at least one of the wellbore junction tubular legs. 89.The method according to claim 88, wherein the actuating step isperformed after the conveying step and before the displacing step. 90.The method according to claim 88, wherein the actuating step isperformed by applying pressure to the tubular string.